Department of Mechanical Engineering (ME)http://hdl.handle.net/20.500.12228/402024-03-29T13:27:34Z2024-03-29T13:27:34ZA Cross-sectional Study of Work-Related Musculoskeletal Disorders among Construction Workers in BangladeshRahman, Md. Sumonhttp://hdl.handle.net/20.500.12228/8352020-02-27T21:00:17Z2019-12-01T00:00:00ZA Cross-sectional Study of Work-Related Musculoskeletal Disorders among Construction Workers in Bangladesh
Rahman, Md. Sumon
The construction activities are closely associated with many occupational injuries. Work-related musculoskeletal disorders (WMSDs) are the most common occupational injuries faced by construction workers. WMSDs refer to a set of painful illnesses of human body muscles, tendons, nerves, ligaments, joints, etc. The construction workers also face injuries from the work site accidents. Most of the accident occurs in the construction site by falling objects on the worker’s body, workers fall from the height, electrocution, etc.. The workers feel pain in different body parts, sometimes become partial or permanent disable due to worksite accidents. There are many factors associated with the occupational injuries. Different researchers from different countries have studied the work-related musculoskeletal disorders of construction workers. As far, I know, no researchers have studied these types of disorders on Bangladeshi construction workers. Keeping this view in mind, the study investigated the work-related musculoskeletal disorders and accidental injuries among the Bangladeshi construction workers. This study also tried to find out the factors associated with Work-related musculoskeletal disorders (WMSDs). For this purpose, a cross-sectional study was conducted through a structured and Modified Nordic Questionnaire. The structured questionnaire contained the socio-demographic characteristics, the physical risk factors, environmental risk factors, and the equipment risk factors. The Modified-Standardized Nordic Questionnaire (MNDQ) is used to identify the musculoskeletal pains on different body parts over the previous year. All the questionnaires were two categories as an open-end and yes/no. In this study, a total of 450 (362 males and 88 females) construction workers aged between 18 to 65 years old were taken from the different construction sites at Jashore, Khulna and Satkhira, Bangladesh. Their main activities were mixing sand and cement, ironwork, lifting and carrying mortar, bricklaying, plastering, concrete laying and tiles fitting. The results found that overall 70.2% of workers reported that they had suffered at least one body part injury over the last 12 months. Among the nine body parts, lower back (49.80%) was the highest suffered body part and a thigh (9.60%) was the lowest suffered part. It is found the occurrences of work-related musculoskeletal disorders (WMSDs) were associated with socio-demographic characteristics such as gender, age, work experiences, working time, and working types. To minimize the work-related musculoskeletal disorders workers suggested to provide safety aid (26.70%), provide proper training and education (19.50%), to design hand tools in ergonomically (24.90%), ensuring good working environment (26.40%), and proper use of the personal protective equipment (21.80%). Most of the workers (32.20%) did not specify how to prevent work-related musculoskeletal disorders.
About 60.70% of the participant experienced with accidents during their work in the construction site. Most of the accidents occurred by the falling objects on the worker’s body (19.10%), workers fall from the height (25.30%), electrocution (3.30%) respectively. Based on the data most of the workers (29.80%) injured in different body regions due to the worksite accidents. The workers also identified the causes of accidents such as personal negligence, lack of work experience, improper use of PPE (Personal Protective Equipment), absence of a good working environment, the overload of work, and lack of safety facilities. Above allcauses, the lack of safety facilities (42.80%) reported as the highest reason behind the accidents. It is found from this study that the prevalence of work-related musculoskeletal
disorders and accidental injuries among the Bangladeshi construction workers are high. Finally, the author had made some recommendations for both workers and management of the construction sites.
This thesis is submitted to the Department of Mechanical Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Mechanical Engineering, December 2019.; Cataloged from PDF Version of Thesis.; Includes bibliographical references (pages 54-58).
2019-12-01T00:00:00ZWear Rate Comparison of Different Impeller Materials for Pumping Various Types of SlurryKarmokar, Sandiphttp://hdl.handle.net/20.500.12228/7712020-02-16T21:00:12Z2019-05-01T00:00:00ZWear Rate Comparison of Different Impeller Materials for Pumping Various Types of Slurry
Karmokar, Sandip
Erosive wear can as defined as solid deduction process from a solid superficial due to frictional action between the slurry and surface. It is triggered by the effect of solid particles contains by slurry in contradiction of the surface of a solid body. The impacting solid particles progressively take away material from the solid superficial due to cutting action. Erosive wear is a significant factor for design centrifugal pump impeller and pumping slurry. Impeller wear is a very common phenomenon for every industry and slurry transportation system. Slurry erosion takes place in our civilized life such as thermal power plants, hydro power plants, excavating businesses, food handling productions, construction and civil works, oil field, solid-liquid hydro transportation systems, coal liquefaction plants, and boilers.
As the Slurry erosion related machinery or equipment demand is becoming so acute day-by-day, scientists are giving efforts on the aptitudes of utilizing applicable technologies to reduce erosion from the related machinery or equipment. As a result performance of slurry equipment, dependability and operation lifetime of the slurry equipment are significantly improved.
Slurry erosion tester ordinarily used to investigate the comparative erosion behavior and characteristics of various materials expose to slurry at moderate solid concentrations. Slurry erosion tester is a modest and convenient apparatus to determine slurry erosion of different equipment.
In this project, a pin mill type slurry-pot wear tester has been made. Total four types (aluminum, brass, mild steel and cast iron) of material with two geometries (flat bar and impeller) have been made for test. Slurry has been made by mixing silica sand and water by at required ratio in a GI container (slurry pot). All samples has been tested by the developed apparatus and determined wear rate with respect to various parameters like slurry density, shaft speed, impact angle and time. This apparatus is used for performing experiments on numerous samples of dissimilar materials exposed to slurry erosion.
In this experiment, total four types of impeller material with two geometries is used for testing at different operating condition such as impact angle, velocity, density and time. Among the eight samples brass is more erosive for both type of geometries (Flat bar and Impeller). On the other hand, cast iron is less erosive for impeller type geometry (45-degree impact angle) but for flat bar type geometry (0-degree impact angle) mild steel is less erosive. If impact angle and density are increased, erosion is found to increase for all types of materials and geometries. From the obtained results, it is clear that by this testing apparatus different types of materials can be tested and suitable pump impeller materials for different application can be found out.
This thesis is submitted to the Department of Mechanical Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Engineering in Mechanical Engineering, May 2019.; Cataloged from PDF Version of Thesis.; Includes bibliographical references (pages 56-57).
2019-05-01T00:00:00ZWear Rate Comparison of Different Impeller Materials for Pumping Various Types of SlurryKarmokar, Sandiphttp://hdl.handle.net/20.500.12228/7682020-11-03T21:00:14Z2019-05-01T00:00:00ZWear Rate Comparison of Different Impeller Materials for Pumping Various Types of Slurry
Karmokar, Sandip
Erosive wear can as defined as solid deduction process from a solid superficial due to frictional action between the slurry and surface. It is triggered by the effect of solid particles contains by slurry in contradiction of the surface of a solid body. The impacting solid particles progressively take away material from the solid superficial due to cutting action. Erosive wear is a significant factor for design centrifugal pump impeller and pumping slurry. Impeller wear is a very common phenomenon for every industry and slurry transportation system. Slurry erosion takes place in our civilized life such as thermal power plants, hydro power plants, excavating businesses, food handling productions, construction and civil works, oil field, solid-liquid hydro transportation systems, coal liquefaction plants, and boilers.
As the Slurry erosion related machinery or equipment demand is becoming so acute day-by-day, scientists are giving efforts on the aptitudes of utilizing applicable technologies to reduce erosion from the related machinery or equipment. As a result performance of slurry equipment, dependability and operation lifetime of the slurry equipment are significantly improved.
Slurry erosion tester ordinarily used to investigate the comparative erosion behavior and characteristics of various materials expose to slurry at moderate solid concentrations. Slurry erosion tester is a modest and convenient apparatus to determine slurry erosion of different equipment.
In this project, a pin mill type slurry-pot wear tester has been made. Total four types (aluminum, brass, mild steel and cast iron) of material with two geometries (flat bar and impeller) have been made for test. Slurry has been made by mixing silica sand and water by at required ratio in a GI container (slurry pot). All samples has been tested by the developed apparatus and determined wear rate with respect to various parameters like slurry density, shaft speed, impact angle and time. This apparatus is used for performing experiments on numerous samples of dissimilar materials exposed to slurry erosion.
In this experiment, total four types of impeller material with two geometries is used for testing at different operating condition such as impact angle, velocity, density and time. Among the eight samples brass is more erosive for both type of geometries (Flat bar and Impeller). On the other hand, cast iron is less erosive for impeller type geometry (45-degree impact angle) but for flat bar type geometry (0-degree impact angle) mild steel is less erosive. If impact angle and density are increased, erosion is found to increase for all types of materials and geometries. From the obtained results, it is clear that by this testing apparatus different types of materials can be tested and suitable pump impeller materials for different application can be found out.
This thesis is submitted to the Department of Mechanical Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Engineering in Mechanical Engineering, May 2019.; Cataloged from PDF Version of Thesis.; Includes bibliographical references (pages 56-57).
2019-05-01T00:00:00ZSolving Multi-Objective Assignment Problem with Decision Maker’s Preferences by Using Genetic AlgorithmRahman, Md. Mahbuburhttp://hdl.handle.net/20.500.12228/5222019-07-21T21:00:13Z2019-06-01T00:00:00ZSolving Multi-Objective Assignment Problem with Decision Maker’s Preferences by Using Genetic Algorithm
Rahman, Md. Mahbubur
The multi-objective assignment problem is basically the N men –N tasks problem, where a single task has to be assigned to an individual with a view of optimizing the outcomes. A common challenge is to address the conflicting objectives which produce Pareto–optimal solutions. The main feature of the work is- normalizing all the criteria into a single scale regardless of their measurement units and their demand of minimum or maximum, which reliefs the researchers from careful attention in quantifying the quality criteria. The methodology also included the decision maker’s preferences regarding the objectives. While solving the problem through a genetic algorithm, a new encoding scheme is used together with a partially matched crossover (PMX). The working principle of the proposed algorithm is illustrated with a numerical example and its effectiveness has been compared with some well-established methodologies. It is found that the proposed algorithm provides a better solution with minimal computational effort.
This thesis is submitted to the Department of Mechanical Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Mechanical Engineering, June 2019.; Cataloged from PDF Version of Thesis.; Includes bibliographical references (pages 43-45).
2019-06-01T00:00:00Z